The aim of this project is to describe the levels at which stutterers show deficits in temporal control of speech production. Building upon paradigms which have previously demonstrated differences between stutterers and normals in reaction time and segmental duration in speech, a series of studies will be carried out to examine successively more complex levels of motor timing control in stutterers. Specifically, experiments were devised to: a) assess temporal intactness of auditory processing in stutterers; b) assess adequacy of response latency to speech and non-speech stimuli, utilizing for responses both non-speech structures as well as speech structures in speech and non-speech modes; c) assess temporal accuracy of imitation of trains of various speech stimuli (presented at various tempos and rhythms) with responses of various speech structures in speech and non-speech modes; d) assess ability to maintain temporal accuracy in shadowing phonetically and rhythmically unpredictable stimulus trains; e) assess temporal control of coarticulation in stuttered and fluent contexts. A small group of severe adult male stutterers (and matched normal controls) will be used for the entire set of studies. Levels of temporal control which reveal devicits will be reexamined with a larger group of subjects involving stutterers of differing severities. Investigation of temporal control will eventually be extended to stutterers of both sexes and a large range of ages and developmental levels. Information from these studies will be critical for: (1) defining domains of temporal control deficit which must be taken into account when building models of stutterering; (2) providing a scaffolding to describe the development of stuttering, from onset to adult; and (3) devising measures which may be used to identify children who are at risk for becoming stutterers, in whom the disorder may be prevented.